Houses with central air conditioning typically have what is called a split system. The split system consists of two primary components: 1) the evaporator coil inside the house, and 2) the condensing unit outside of the house. These two components are connected with refrigerant lines.
FIG. 1 shows a typical HVAC system found in most residential homes. In a typical air conditioning system, a refrigerant circulates through a loop of copper tubing 101 that runs between the outdoor condenser coil 102 and the indoor evaporator coil 103. The refrigerant traveling between the two coils absorbs heat from the inside room and releases it outside. In the process, the refrigerant cools the evaporator coils.
Typically the evaporator coil 103 is located inside the housing of a furnace 120. It is made up of refrigerant piping loops and usually designed in an A-shape, as shown in FIG. 1. The furnace blower 105 blows air across and through the evaporator coil 103, and the refrigerant loops cool the air as it passes through the coil, causing water vapor in the air to condense to liquid and collect on the coil. The condensate then drips into a drain pan 104 located under the evaporator coil 103.
The drain pan 104 is usually built into the unit by the manufacturer. There is a condensate line 106 connected to the outlet hole in the drain pan. This condensate drain line is piped to either a floor drain or to the outside. Many times instead of a pipe, a hose is used for the condensate drain line.
All HVAC coil manufacturers use some type of clip for attaching the coil to the drain pan. However, existing clips do not lock into place and eventually pull apart under mechanical load. Therefore, it would be desirable to have a retaining clip for the drain pan that locks into place and is more resistant to load than current designs.